Composition for use in sand molding



Patented Dec. 1, 1953 UNITED STATES PATENT OFFICE COMPOSITION FOR USE INSAND MOLDING Connor B. Shanley, Kirkwood, M0.

N Drawing. Application September 19, 1949, Serial No. 116,618

2 Claims. 1

This invention relates in general to certain new and useful improvementsin methods of sand molding and compositions for use in conjunctiontherewith.

In the preparation of sand molds for use in the manufacturing ofmetallic castings, it is standard practice to lay a pattern on a moldingboard and place the drag portion of the flask around it. Molding sand isthen riddled or sifted over the pattern until the drag is partiallyfilled. and this sand is rammed. Thereupon, additional sand is siftedinto the drag and rammed and this process is repeated as many times asmay be desired until the sand projects somewhat above the edge of thedrag. The surplus or projecting sand is struck off with a straight edgeuntil it is flush with the edge of the drag. Loose sand is thensprinkled on this surface and a bottom board placed on it. Dependingupon the nature of the mold, the drak may be vented in any appropriatemanner.

The drag, with the pattern and bottom board in position, is turned overand the molding board removed, exposing the joint or parting face andcope side of the pattern. This parting face is usually finished byslicking with a broad trowel until the surface is very smooth and firm,whereupon it is dusted with parting sand and the cope portion of theflask put in place. The cope is then filled and rammed in substantiallythe same manner as the drag.

When the ramming is completed, the cope is lifted offv for finishing themold. Various conventional operations are then performed, such asremoval of the pattern, installation of chaplets, formation of a runnerfrom the gate to the mold cavity, and any smoothing or facing operationswhich the particular circumstances may require. In the course of theseoperations, the parting face of the cope is usually slicked down, so asto make a very smooth juncture with the parting face of the drag. In anycase, when all the necessary molding operations are completed, the copeis replaced in position on top of the drag and weighted down or the copeand drag are suitably clamped together to receive the molten metal. Inthe present state of molding technique, it is common practice to useremovable flasks and, in order to do so, provision must be made to holdthe parts of the mold in precise alignment against lateral shiftingalong the parting faces.

At the present time, it is common practice to insert dowel pins orspikes through the two parts of the mold, but such means do not providetrue precision of alignment. Furthermore, dowel pins and the like becomeforeign substances which render the sand unfit for re-use and must beremoved by methods which have been found to be comparatively expensiveand time-consuming.

It is, therefore, one of the primary objects of the present invention toprovide a simple, quick, and economical method of securing the parts ofa sand mold together which makes it possible to achieve precisealignment of the cavity-forming portions of the mold.

It is another object of the present invention to provide a method ofsecurely joining the separate parts of a sand mold together oversubstantially the entire area of their parting faces without theintroduction of foreign sub stances which will render the molding sandunfit for subsequent use or will require the sand to be subjected to areclamation process which is both expensive and time-consuming.

It is also an object of the present invention to provide a uniquecomposition which may be employed for joining together the matchingparts of a sand mold and holding them securely in precise alignmentduring subsequent handling and use. I It is a further object of thepresent invention to provide a composition of the type stated which willnot contaminate the sand or otherwise ren der it unfit for subsequentre-use.

It is likewise an object of the present invention to provide acomposition of the type stated which will become intermixed with themolding sand after it is removed from around the finished casting andwill improve the molding qualities of such sand when it is laterre-used.

With the above and other objects in view, my invention resides in thenovel processes and compositions of matter presently described andpointed out in the claims.

Broadly speaking, the present invention resides in coating the partingfaces of the cope and drag or similar cavity-forming components of asand mold with an adhesive consisting of a mixture of bentonite, water,and curbay. Curbay, as defined on page 118 of the Zimmerman and LavineHandbook, published 1946 by Industrial Research Service, is adark-colored liquid of a syrupy consistency, obtained from the liquidresidue in the manufacture of alcohol from molasses and consists ofcomplex mixtures of vegetable gums, unfermentable sugars, inorganicsalts, and water. This adhesive is capable of becoming thoroughlyintermixed and, in effect, disappearing into the molding sand after ithas been knocked loose from the finished casting without impairing thequality of the sand for subsequent molding use. Thus, the adhesivesubstance will in the first instance serve to hold the mold partstogether, but will not become a foreign substance in the molding sandupon subsequent re-use.

For purposes of illustration and not by way of limitation, the followingare specific examples of an adhesive material forming a part of thepresent invention:

In. preparing the above compound, the bentonite and water are mixed andthe curbay added slowly to form a thorough homogeneous liquid.Thereupon, the seacoal, which is finely ground or pulverized,low-volatile, substantially sulphurfree coal, is stirred into themixture to produce a fluid product having a specific gravity rangingapproximately from 60 degrees B. to 100 degrees B. It should beunderstood that the foregoing percentages by weightv have been found togive preferred forms of adhesive composition but variations in thesepercentages have been found to be fully effective over fairly wideranges.

In accordance with the present invention, the parting face of the copeand drag are made smooth and hard through jolting or ramming against asmooth plate or board. If necessary, the parting faces are carefullyslicked down with a hand trowel or by any other suitable method so thatthe two parts of the mold will fit tightly and precisely together. Thesmooth parting faces are then coated with the adhesive of the presentinvention and the twoparts of the mold placed together. When theadhesive has set or dried, the flask is removed and it will be foundthat the two parts of the mold are securely adhered together. In fact,the adhesive of the present invention is so highly efiective that thetwo parts of the mold will be extremely hard to separate or displacefrom each other almost immediately after the two adhesive coatedsurfaces are pressed together.

Subsequently, after the casting has been poured and cooled, the moldingsand may be knocked away or otherwise removed from the casting and theadhesive material will become uniformly and intimately mixed with thesand in such a manner that it will not in any way interfere with thesubsequent use of the sand. As a matter of fact, the residual componentsof the adhesive, which are thus incorporated into the sand uponsubsequent use, will improve, rather than impair, its molding qualities.

It should be understood that changes in the methods, compositions,percentages, and combinations above set forth may be made withoutdeparting from the nature and principle of my invention.

Having thus described my invention what I claim and desire to secure byLetters Patents is.-

I. An adhesive for joining together the parts of a sand mold consistingof the following composition:

Percent by weight Bentonite 10 to 20 Water 40 to 55 Curbay 30 to 2; Anadhesive for joining together the parts of a sand mold consisting of thefollowing composition:

Percent by weight Bentonite 10 to 20 Water 40 to Curbay 30 to 45 Seacoal2 to 5 CONNOR B. 'SHANLEY.

References Cited in the file Of this patent UNITED STATES PATENTS NumberName Date 632,579 Lundin Sept. 5, 1899 1,576,248 Robeson Mar. 9, 19261,673,357 Hanley June 12, 1928 1,837,877 McDowall Dec. 22', 19311,867,382 Sampson July 12, 1932 1,889,905 Saeger Dec. 6, 1932 1,893,683Saeger Jan. 10, 1933 1,897,149 Saeger Feb. 14, 1933 2,169,279 OysterAug. 15, 1939 2,201,131 Jungersen May 14, 1940 2,270,770 Ray Jan. 20,1942 2,348,155 Shanley May 2, 1944 2,380,945 Collins Aug. 7, 19452,525,175 Keyser Oct. 10, 1950

1. AN ADHESIVE FOR JOINING TOGETHER THE PARTS OF A SAND MOLD CONSISTINGOF THE FOLLOWING COMPOSITION: